1. Field of the Invention
The present invention relates to a pedestrian protection apparatus for a vehicle, and in particular to an improved structure of the pedestrian protection apparatus disposed at a lower region of a front of the vehicle and arranged to apply a counterforce to a leg portion of a pedestrian by contact with the leg portion of the pedestrian that has collided or contacted with a front face of the vehicle, thereby protecting the leg portion of the pedestrian.
2. Description of the Related Art
In vehicles such as automobiles, there are conventionally disposed, at a front face, a rear face, or side faces, of the vehicles, various types of protection apparatus which absorb an impact energy generated upon a collision, for thereby protecting the vehicle body and vehicle passengers. In recent years, there is also disposed, at the front face of the vehicle, an apparatus for protecting a pedestrian upon collision (contact) of the pedestrian with the front face of the vehicle.
As one type of the pedestrian protection apparatus for a vehicle (hereinafter, simply referred to as the pedestrian protection apparatus), there is known a leg-sweep apparatus. Generally, the leg-sweep apparatus is disposed at a lower region of the front of the vehicle such as an inside of a front bumper and a portion below the front bumper. The apparatus is arranged to contact with a leg portion of the pedestrian upon collision of the pedestrian with the front face of the vehicle, whereby the leg portion of the pedestrian is swept or scooped to cause the pedestrian to be thrown toward a member such as a hood (bonnet) that can absorb the impact. Thus, the protection and safety of the pedestrian can be assured.
The pedestrian protection apparatus is expected to have a structure that can reduce the damage to the leg portion of the pedestrian that has collided with a front portion of the pedestrian protection apparatus. In order to satisfy this expectation, for example, JP-A-2007-55543 and JP-A-2010-179671 each disclose a pedestrian protection apparatus that is a resin molded product disposed at a lower region of a front of the vehicle so as to extend in a front to back direction of the vehicle. The resin product integrally includes a front section that includes a reinforcing portion and a rear section that is fixed to a vehicle component.
The pedestrian protection apparatus disclosed in JP-A-2007-55543 includes a resin plate member which is disposed at a lower region of a front of the vehicle so as to extend in a front to back direction of the vehicle. At the rear section of the plate member, it is bolted to a vehicle component. At the front section of the plate member, planar vertical ribs are integrally provided at a plurality of positions on one surface thereof with a predetermined distance therebetween in a vehicle width direction such that the planar vertical ribs extend in the front to back direction of the vehicle while being opposed to each other in the vehicle width direction. Further, between the vertical ribs on the front section of the plate member, planar horizontal ribs extending in the vehicle width direction are integrally provided so as to connect the opposing vertical ribs. Accordingly, the pedestrian protection apparatus includes, at the front section of the plate member, a rib structure having the vertical ribs and the horizontal ribs in combination. Further, the rib structure provides a reinforcing portion at the front section of the pedestrian protection apparatus. The reinforcing portion improves the strength of the front section, i.e., improves the deformation strength against the load input from the front side of the vehicle to the rear side.
The pedestrian protection apparatus disclosed in JP-A-2010-179671 includes upper reinforcing beads and lower reinforcing beads that are each alternately arranged at a front section of a resin plate member. The upper reinforcing beads each protrude upward with an angular U-shaped cross section and extend in the front to back direction of the vehicle while opening downward. The lower reinforcing beads each protrude downward with an angular U-shaped cross section and extend in the front to back direction of the vehicle while opening upward. Further, inside each of the upper and lower reinforcing ribs, a connection rib extending in the vehicle width direction is integrally provided between opposing vertical walls (vertical ribs) so as to connect the vertical walls. In other words, in this pedestrian protection apparatus, the reinforcing portion is provided at the front section thereof by the upper and lower reinforcing beads and the connecting ribs that are provided at the front section of the plate member. Accordingly, the rigidity of the front section (the deformation strength against the load input from the front side of the vehicle to the rear side) of the pedestrian protection apparatus is improved.
As described above, in the conventional pedestrian protection apparatus, the reinforcing portion is provided at the front section to improve the rigidity of the front section. As a result, a load-displacement curve showing the relationship between the impact load generated upon the contact of the leg portion of the pedestrian and the deformation (displacement) amount of the pedestrian protection apparatus has an almost ideal rectangular wave shape. Thus, the impact generated upon the contact of the leg portion of the pedestrian is efficiently and sufficiently absorbed, thereby effectively reducing the damage of the leg portion of the pedestrian.
However, various studies conducted by the present inventors revealed that the structure of the above-described conventional pedestrian protection apparatus has the following problem.
Generally, the pedestrian protection apparatus that is disposed at a lower region of a front of the vehicle receives the air at the upper and lower surfaces thereof during driving of the vehicle. Thus, it is preferable that the pedestrian protection apparatus have a structure that cannot only protect the pedestrian, but also can guide the airflow smoothly to the rear side. Such a structure improves aerodynamic performance of the vehicle, leading to an improvement of fuel efficiency.
However, in the conventional pedestrian protection apparatus, the reinforcing portion provided at the front section includes the planar horizontal ribs or the connecting ribs that extend in the vehicle width direction at the upper or lower surface of the front section. Thus, in the case where the conventional pedestrian protection apparatus is provided at the lower region of the front of the vehicle, during driving of the vehicle, the air contact with the horizontal ribs or the connection ribs so that the airflow is prevented by the horizontal ribs and the connecting ribs. In other words, in the conventional pedestrian protection apparatus, the horizontal ribs and the connection ribs function as aerodynamic drag (air resistance), which make it difficult to guide the airflow to the rear side. Thus, the conventional pedestrian protection apparatus can surely protect the pedestrian by being provided at the lower region of the vehicle, but may deteriorate the aerodynamic performance at the lower region of the vehicle.